Hi Han Shot First,
Welcome to the Mattress Forum! 
I am not familiar with Pangeabed. They were incorporated in April of 2016, and are one of over now 100 bed-in-a-box online companies. While their mattresses are made in the USA, I’m not sure of the source of their polyfoams. Their latex is from Talalay Global.
Can you help me with where you found the detailed descriptions of each layer of foam in the Pangeabed? I can’t find that on their web site. Was that from a chat transcript? Or are you affiliated with Pangeabed?
For the Pangeabed, you’d want to find out the density of the 5/8" of polyfoam in the quilt, but even if it is lower in density it’s a smaller amount. The 1.5" of Talalay latex is a good quality material, but they don’t list the ILD (not important for quality). The 1.5" of memory foam is 3 lb., and that’s a lower quality than I would recommend. If their 7" polyfoam core is 1.8 lb. as you stated, that would be good and the minimum I would recommend. Overall I would advise caution with this mattress using the 3 lb. memory foam. You can read more about my recommendations of foam densities in the durability guidelines here.
The Nest Bedding Love & Sleep Mattress mattress is a newer entry in the budget range, and does offer one of the better values in the lower price points. Regarding the foams, the Energex polyfoam is a good quality 2.8 lb. polyfoam that does allow for better repositioning than memory foam, and it is more breathable. There is more about some of these newer high performance polyfoams here in post #2. It is not meant to be like latex. The 1" SmartFlow Air Flow layer is 2 lb. polyfoam, and the 6" core is 1.8 lb. as you already know. The quality of these foams are good and I would only have concerns for those in the 200 pounds or above range, as the base foam of 1.8 lb. would be lower than I would recommend for higher weight ranges.
Nest Bedding is a member of this site which means that I think very highly of them and that I believe that they compete well with the best in the industry in terms of their quality, value, service, knowledge, and transparency.
These mattresses are different styles of products, marketed to different segments, with the Love and Sleep being a good value in the budget range.
I hope that helps you a bit with the differences between the two products.
Phoenix